Permeability of Hybrid Reinforcements and Mechanical Properties of their Composites Molded by Resin Transfer Molding

Schmidt, Tuany Rafaeli; Goss, Thiago Marcon; Amico, Sandro Campos; Lekakou, Constantina

doi:10.1177/0731684408093974

Cited by 34 publications

(35 citation statements)

References 20 publications

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“…7). The experimental details are presented by Schmidt et al (2009). Figure 7 shows a good agreement between experimental and numerical results, presenting a maximum difference of 8.12% in Case 2.…”

Section: P C C T C T C T C T C T C T C T Pamentioning

confidence: 56%

Three-dimensional numerical modeling of RTM and LRTM processes

Isoldi¹,

Oliveira²,

Rocha³

et al. 2012

J. Braz. Soc. Mech. Sci. & Eng.

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Section: P C C T C T C T C T C T C T C T Pamentioning

confidence: 56%

Three-dimensional numerical modeling of RTM and LRTM processes

Isoldi¹,

Oliveira²,

Rocha³

et al. 2012

J. Braz. Soc. Mech. Sci. & Eng.

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“…Outra possibilidade é a degasagem por sonificação normalmente em um banho de ultrassom [12] . Estes processos, apesar de eficientes, exigem equipamentos apropriados que muitas vezes não estão disponíveis.…”

Section: -Efeito De Aditivos Desaerantes Nas Características De Compóunclassified

Efeito de Aditivos Desaerantes nas Características de Compósitos de Epóxi/Fibras de Vidro

2014

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Resumo: A presença de vazios é um importante fator a afetar as propriedades de compósitos poliméricos. Existem várias causas para a formação de vazios, entre elas, o aprisionamento de gás (frequentemente gás úmido) durante o processo de impregnação dos reforços fibrosos com resina e os voláteis gerados durante a formulação da resina. A quantidade de bolhas de ar aprisionadas pode ser, por vezes, reduzida se o sistema de resina é sujeito a um processo de desgaseificação por vácuo ou pelo uso de aditivos químicos especiais. O objetivo deste trabalho é investigar o efeito de um agente desaerante nas propriedades finais de compósitos de resina epóxi moldados pelo processo de RTM utilizando como reforço mantas e tecidos de fibras de vidro. Os compósitos produzidos foram avaliados quanto as suas propriedades de tração, flexão, dureza, short beam e análise dinâmico mecânica (DMA). Em geral, a utilização do aditivo desaerante não provocou alterações significativas nas propriedades mecânicas, tais como resistência e módulo de tração e flexão, as quais são determinadas principalmente pelo tipo e fração volumétrica de fibras. Contudo, os resultados de resistência ao cisalhamento e de dureza mostram um efeito positivo com a inclusão do agente desaerante, levando à melhora na qualidade dos compósitos. Palavras-chave: Compósitos, vazios, sistema epóxi, desaerantes. The Effect of Degassing Agents on the Characteristics of Epoxy/Glass Fiber CompositesAbstract: The presence of voids is an important factor to affect the properties of polymer composites. There are several causes for void formation, such as gas entrapment (most often wet air) during impregnation of the fibrous reinforcement with resin and volatiles arising from the resin system itself. The amount of entrapped air bubbles can sometimes be reduced if the resin system is subjected to a degassing process (e.g. aided by vacuum) or by using special chemical additives. The aim of this research is to investigate the effect of a degassing agent on the final properties of epoxy composites molded by RTM using glass-fiber mats or plain-weave cloths. The produced composites were evaluated under tensile, flexural, hardness and short beam testing, along with dynamical mechanical analysis (DMA). In general, the use of the additive did not ensure significant improvement in those mechanical properties that are primarily determined by the type and content of the fibrous reinforcement, such as tensile and flexural strength and modulus. However, the short beam strength and hardness results showed a positive effect with the inclusion of the additive, leading to better quality composites. Keywords: Composites, voids, epoxy, degassing agents. IntroduçãoA presença de defeitos em compósitos estruturais é um dos pontos críticos para a aplicação destes materiais. Dentre os defeitos que podem ser oriundos da sua produção, pode-se citar regiões ricas em resina ou fibra, fibras distorcidas ou dobradas, presença de contaminantes e vazios, sendo este último de grande preocupação, pois são difíceis...

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“…Since the injection pressure was not constant, it was necessary to define an equation representing its variation as a function of the time. For that, the experimental data reported by Schmidt et al (2009) was used to find a polynomial adjustment curve for the injection pressure (in Pa) as follows:…”

Section: A Verification and Validation Of The Computational Modelingmentioning

confidence: 99%

Computational Modeling of RTM and LRTM Processes Applied to Complex Geometries

Letzow

Souza

Isoldi

2012

RETERM

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Light Resin Transfer Molding (LRTM) is a variation of the conventional manufacturing process known as Resin Transfer Molding (RTM). In general terms, these manufacturing processes consist of a closed mould with a preplaced fibrous preform through which a polymeric resin is injected, filling the mold completely, producing parts with complex geometries (in general) and good finish. Those processes differ, among other aspects, in the way that injection occurs. In the RTM process the resin is injected through discrete points whereas in LRTM it is injected into an empty channel (with no porous medium) which surrounds the entire mold perimeter. There are several numerical studies involving the RTM process but LRTM has not been explored enough by the scientific community. Based on that, this work proposes a numerical model developed in the FLUENT package to study the resin flow behavior in the LRTM process. Darcy’s law and Volume of Fluid method (VOF) are used to treat the interaction between air and resin during the flow in the porous medium, i.e. the mold filling problem. Moreover, two three-dimensional geometries were numerically simulated considering the RTM and LRTM processes. It was possible to note the huge differences about resin flow behavior and filling time between these processes to manufacture the same parts.

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Permeability of Hybrid Reinforcements and Mechanical Properties of their Composites Molded by Resin Transfer Molding

Cited by 34 publications

References 20 publications

Three-dimensional numerical modeling of RTM and LRTM processes

Three-dimensional numerical modeling of RTM and LRTM processes

Efeito de Aditivos Desaerantes nas Características de Compósitos de Epóxi/Fibras de Vidro

Computational Modeling of RTM and LRTM Processes Applied to Complex Geometries

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